It is difficult to manufacture components with complex internal geometries. Although precision investment casting is often used to manufacture components with internal cavities, the complexity of the passages is limited by the casting core and the ability to flow material within a mold. Intricate cores are fragile, and may not withstand the casting process. Machining of internal features is usually limited to line-of-sight processes.
There are various additive manufacturing techniques such as Direct Laser Metal Sintering (DMLS) that are capable of building components layer-by-layer from sintered powder. Although such techniques are suitable for making prototypes and for limited production, they are not economical for large scale production. Additionally, the surfaces of laser-sintered materials can be unacceptability rough.
In stacked laminate construction, a component is constructed from multiple layers of sheet or foil material. Each individual sheet can be easily machined to form cutouts. The component is then built by stacking the sheets. The sheets can be registered with the cutouts aligned to form complex internal geometries. A limitation of the stacked laminate approach is the ability to reliably bond each layer. Some materials such as superalloys Haynes® 230 and 282 that are otherwise desirable are difficult to bond into a laminated structure. This limits the choice of materials that can be used for laminated construction.